The mouthpiece is often overlooked and divers / snorkelers put up with whatever they get. There are many options available to get it just right including custom moldable mouthpieces.

Small bite? Get a small mouthpiece. There are even youth sizes. Uncomfortable rubbing on your gums? There are many choices with minimal bite surfaces. You know those pillows that sink in slowly as you lay your head and they mold to your head? You can get a mouthpiece that does the same thing. There are many different types of bite surfaces. Some that minimize your tension, that grip your teeth, and even stick to the roof of your mouth. Between $6 and $12, you should be able to get a very comfortable one that fits just right.

My personal favorite is a moldable version. They are a bit more expensive at $26 to $38 but they fit perfectly and rarely do you ever need another one. Heat them up in hot water then bite down to make a perfect mold of your teeth. Very little bite force is needed as they almost stick to your teeth. So comfortable you never even think about your mouthpiece again. As I love to say, "A luxury not a necessity, but oh what a luxury a comfy mouthpiece is.